Telephone system.



W. W. DEAN. TELEPHONE SYSTEM APPEIOATION FILED JEN 19, 1903. RENEWED FEB. 27, 1907- PATENTED SEPT.. 17, 1907.

WWW fizz/24 the United States of America, and residing at Chicago,

UNITED STATES,

WILLIAM W. DEAN, OF' GHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SWITOHBOARD PATENT OFFICE.

& SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

' Specification of Letters Patent.

Patented Sept. 17,1907.

Application filed June 19,1903, SerielNo. 162,199. Renewed February 27, 19Q7. SerialNo 359,612.

To all whom it may concern: I Be it known that I, WILLIAM W; DEAN, a citizen of It has heretofore been common to associate severalrelays and other auxiliary mechanism with the cord '30 and 3 from the subscribers stations A and D to the cencircuits of the exchange to obtain supervision of the connections, such apparatus often requiring an additional or third strand in the cord circuit.

i In my invention I may dispense with a large part of the auxiliary apparatus and in the preferred form may 'even' dispense with all relays and similar devices and operate the signals direct. In order to accomplish these results in the preferred form of my invention, 1 place the signal in the form of a small incandescent lamp directly in one side of the cord circuit and arrange suitableieontrolling means in the line circuit to control the fiowof operating current to said signal, whereby a minimum of apparatus is required for the complete operation of the exchange system.

My invention is illustrated-in the accompanying drawing in which the figure is a diagram of a telephone exchange system embodying my improvements.

The subscribers lines L and L extend in two limbs 2 traloificeQ.

At the substations-any suitable common battery outfit may be provided, that shown consisting of a bell 4 and a condenser 5 in a permanent bridge of the line conductors, and the transmitter 6 and roceivcr=7 in a bridge I of said conductors that is normally opened by means of the central off ce. v

At the central oflice each lineis fitted in the usual,

sirejd numben. grounded through a movable contact) of the cut-01%. relay R, whose winding is logged to ground fromthc'" sleeve conductor- 1010f the jacks, said conductorjZ bing I th e switch-hook 8. This apparatus is intended totypify any usual or desired subscriber s apparatus adapted for use in connection with a common source of current at manner with a line signal S, preferably in the formof a small incandescent lamp, with an answering jack J and with aplurality of multiple jacks J 2 and J in any He- The line conductor 2 .is norlndlly The limb 3 ofthe, telephone line is connected'with movablecontact 12 ofsaid relay R, which normally connects connected with the tip conductor 11 of the spring. jacks 1 of the linefwhen the said clitoff relay R is energized.

with a conductor 13 leading to the live pole of a central battery B that is common to a large number of lines of the exchange and the opposite pole of which is groun dconductor 13, the back contact of said movable contact being connected-through conductor lo including a resistance 16 with the said tip conductor 11 of the switchboard section of the line. The forward contact of line relay It is connected bymeans of a branch conductor 17 with the moyable contact 18 of thecut-ol'f relay it which normally completes a connection with conductor 19 including the line signal S of the telephone line.

The operators outfit comprises a plurality ol'" cord circuits of the type shown in the drawing, in each of which an answering plug P and a calling plug I are provided with tip and sleeve contacts adapted to register respcc tively with the corresponding contacts of the tclophdne lines when the plugs are inserted therein. The tip contact oi the answering plug is connected by strand t with the winding 20 of the repeating coil W and thence with the grounded pole of thebattery B, while the sleeve contactof the plug is connected by flexible strand 3 and the winding 21 of said repeating coil with the live pole of said battery. In a similar manner the calling plugl has its tip contact joined by strand :5 and winding 22 of repeating coil W with the grounded pole of a second battery 13 also preferably common to a plurality of lines, and its sleeve contact is connected by a similar flexible strand s and winding 23 of repeating coil W with the live pole of this second battery. In the tip strand t I locate a supervisory signal S which is prefcrabl y a small incandescent lamp andwhich is also shunted by nouinductive resistance 24. Similarly a supervisory signal shunted by non-inductive resistance 25 is located in the tip strand 25 connected with the calling plug.

7 The operators receiver 26 together with the secondary of her induction coil 27 and a suitable condenser 28 are adapted to be bridged across one end of the cord circuit by means of the listening key springs 29, 29, while her transmitter 30 and the primary of her induction coil' 27 are in a local circuit charged from any suitable source of current such as the battery B? or B. A ringing gen orator 31 is adapted to be connected between ground and the tip strand t of the cord circuit by the operation of the tip spring of ringing key 33, while simultaneously the forward portion of the sleeve strand s is connected with conductor 34 including a suitable resistance 35 and battery lead 13 with-the live pole of the battery B In the operation of my system, the subscriber] desiring a connection with the subscriber l) takes up his receiver and thereby completes a path l'or ciirrent over the metallic telephone line lroni the central battery li, such current. circulatingow-r the lead til. movablecontact 12 of relay It, through the winding ol relay it, the line conduetoril lo the substation where it passes through the substation instruments and thence back to the central ollice over the line conductor 2 and the movable contact 9 of relay R to ground. The current in this path operates the line relay It" causing it to close the local circuit. ot' the signal S. said local circuit includ-' ing the lead l3, conductor-l4, armature and lront contact of line relay R conductor 17, spring l8 and normal contactot' cut-oil relay It and thence by way of conductor 19 through the signal S to ground. 'lhelightingol' this signal attracts the operatofs attention, who inserts the answering plug P of her cord circuit into the answering jack .l of the telephone line. The insertion of the plug completes a path for current. from the battery li over the sleeve strand sol the cord circuit and over conductor 10 through the windingol' cut-oil relay it to ground. This relay is therefore operated and disconnects the line con doctor 23 l'rotn ground and line conductor 3 from the battery lead l3 and connects them with the corresponding conductors of the switchboard section of the telephone line. The operation of the relay It also opens through its contact. to the local circuit of the line signal S which is therefore rendered inert. t'urrent now tlows from the battery ll over both sides of the metallic telephone line and both sides ol the cord circuit. The signal S must be so adjusted as not to be operated by the current in this metallic path and therefore remains unexposed. 'lhe operatorconnects her instrument with the cord circuit. by means of the listening key 29 and receives the order from the calling subscriber.

Upon learning that subscriber l) is wanted, the operator proceeds to test the idle or busy condition of the line. lithe line is found idle the test rings of the jacks are connected with ground only and since the tip of the calling plug P is likewise connected with ground no flow of current. results over the strand t of the cord circuit and the operator knows that the line is idle; but it connected with another subscriber for conversation the sleeve contacts of, the line are connected with the live pole of either the battery B or B since said batteries are common to all of the cord circuits, and the appli( -ationol' the tip of the testing plug to said; test rings completes a path for current from said live pole ot the battery toground over the tip strand 1?.

.'lhe flow of current over this path causes a change of potential at. the terminals of the operators bridge and the surge of current theret-hrough is sutlicient to cause a click in her receiver. She is thus informed that the litte is busy. 1

Assuming that the line is found idle the plug P is insertedin the multiple jack of the sa-id line that is upon the operators section of the switchboard and'thp ringing key is operated. The insprtion ol' the plug P completes a path for current over the strand s".l'roin the battery ll through the cutol'l relay R. of the calledline which is thus operated to sever the local circuit ol' the signal is of the wanted line to thereby prevent its operation and to also connect the external line circuit with the switchbon l section. The depression of the ringing key 'iitlillgfl serves to connect the ringing generator 3] with the tip side of the line which sends current out over the telephone line thfough the call bell at the substation and back to the central otlice over the SlCPVL COlKlUCtU! and thence through sleeve spring 33 of the ringing key. conductor 34, resistance 35, conductor iii through battery B to ground. The current from the battery B also circulates through the conductors i3, 34 and 5 through the cut-off relay R to maintain the same actuated (luring ringing. Alter the subscriber has been called but before his response the supervisory signal S is operated.

' lhe path for this operating current is over the conductor l3, branch conductor 14, normal contacts of line relay it", conductor 15, resistance 16 and con- (luctors ll and t to the other pole of the battery B The signal is thereiore operated and indicates thatthe subscriber has not yet responded. Upon his response current from the battery 13 circulates over both sides of the cord circuit and both sides of the telephone line and serves to operate the line relay R This relay in thus operating opens the local circuit of said supervisory signal S and therefore renders the same inert which indicates to the operator that the subscriber has responded. I

During conversation the batteries B and l? are se nd lug current over the lines for the operation of the substation devices. The Voice currents are repeated from one line circuit to the other through the medium of the repeating coil W. The supervisory signals do not now operate since the amount of current they receive is not sullicient to cause them to glow. In case of rupture of thellanip filaments, conversation may still be carried on through the non-inductive resistance 24.

At the termination of the conversation when the subscribers receivers are returned to their books the line relays R are deene'rgized and the local circuits of said supervisory signals are closed through the-back-contactsof said relays. They are accordingly lighted and the operator knows that the conversation is finished and the plugs are accordingly removed, thus restoring all parts to normal condition.

It will be understood that the ground connections are preferably one and the same or the common ofiice re- I turn, that the listening and ringing'spring's may be of any desired type, preferably of the kind in which the springs are simultaneously operated by manual means, and that various other modifications may be made in the inventionwithout departingtirorn the'scope thereof.

1. In a telephone systemfthe combination with a telephone line, of a cord circuit to establish connections'wlth the line for conversation. a central common source of current adapted 'to be connected with the 'line to send.

current titer-cover for conversational purposes, a relay in the line under control of the subscriber, and asupervisory signal asset-lied with the cord clrcuitand controlled by said relay. the operation of said'slgnal being caused by current over one of the talking strands of the cord circuit during a connection and when a subscriber's telephone is not in use, and the said signal being prevented from operation by the lack of a snfiicient flow-of current vo'ver said stand during conversation, substantially as described. I

2. in a telephone systeni, the combination with a ttflm phone line. of'a'cord cireutt to establlshconnectlons for cmiversation. a central common source of current to sup ply current to the telephone line during conversation, and a supervisory signal placed in one of the talking strands common source ofcurrent to send current over the tclephone line, of a cord circuit to establish connections for,

v to operate the samc,'substantially as described.

of the cord circuit, said signal being iriert during conversation, but actuated over a circuit local to the central oiiice during the connection when the subscriber's telephone is not in use, substantially as described.-

3. in a telephone system, the-combination with a metallic telephone line, of a cord circuit to establish connections for conversation, a central common source ot' current to supply current over'tl e metallic telephone line for conversation during connections, and a supervisory signal placed inone of the talking strands of the cord circuit in the path of suchcurrent, said signal receiving insuiflcient current to operate the same during couversir tion but receiving suiiicicnt current from said source to operate the same when thc subscribei' s telephone is not in use, substantially as described.

4; In. telephone system, the combination with a twoconductor telephone line, of a cord circuit to establish connections with the line for conversation, a central common sonrceot current to send current ovcr'thc said line during conversation, a signal in one of the talkingstrands ot the cord circuit, and in the path of such current, means; to prevent said signal operating during, conversation but to operate the same from said sour'cc over aflocalv circuit during the connections and when thesubscrihens telephone is not in use, substantially as described 5. The combination with a telephone line, ofa cord circuit to establish connection forconvcrsation, a central phone line during conversation, a relay in the telephone line under the control of. the subscriber, a supervisor)" signal placed in one 'of'thc talking strands of the cord circuit, and means controlled by said relay to prevent the operation of said signal duringconversation but to permit its operation during connections and when the subserihers telephone is not in use, substantially as described.

6. in-a telephone system, the combination yrith a teleconversationfa central common source of current adapted to send current over the cord circuit during conversation, a supervisory signal located in one of the talking strands or ilie cord circuit in the path of current thereover to supply the subscriber's transmitter during eonversatiom. said signahreceiving lnsulflcie'ni: current during convcrsation to operate the same, and means controlled bythe sub seribcr to permit an operating how of current through' said signal when the subscriber's tolcphoncis not in use 7. in a telephone system, the combination with a telephone line, of a cord circuit to establish connections with, ihc line for conversation, a common battery to send current over the strands of the cord circuit and to the substation during conversation, a supervisory signal located in one of the talking strandsnl the cord circuit, a relay in ihe ielephone line under the control of the subscriber, s (1 signal not recclving'an operating current during con- .ion whereby it is at this time inert, and means eoniroiied by said relay for permitting an operating il ow of current from said source through said signal to operate ii. when the subscriber's iclephone is not in use, substaniiall'y as described.

is. in a telephone system, ihe combination with a ielephone line, olu cord circuii io establish couneclious for conversation, a common source of current adapted lo send rurreui. over lhe cord circuit and ieicphouc line during eouversziiiou, an incandescent lamp placed in our of ihe ialkiiu: sirundsuu' said cord circuii, said lamp brim.- in the puih ol' ('lll'il'lll durin conversation and serving as u supervisour signal, and menus to prcvcnt'suid lump opcrating: during eonversaliou lull. in cause ii's operalion ai. other times during ihe conueeiion, subsluuliaily as iie scribed.

i:roilcd by said scribed.

receiving insuflicientcurrent to operate the same during conversation. and means controlled by said relay to include said lamp in a local circuit when the subscriber's sockets or connection terminals of the line, a cord circuitcoiipcrating therewith to establish connections for conversation and having only two strands each forming part of the talking; circuit, an incandescentlamp located in one of said strands and serving as a supervisory mail, a relay in thetelcphonc line in the, path of current from said source over the telephone line and therefore under the control of the subscriber during connections, said lamp be in in the path of current over the telephone line during conversation but receiving an insufficient amount of current at such time to operate the same, and a local circuit closed by said relay when deincrgized to include said lamp and source whereby it then receives suflieient current to be lighted, substantially as described.

11. In a telephone system, the combination with a tele phone line, of a line signal therefor, a line relay to coa troi said signal; a cord circuit-to establish connections with the line, for conversation, an incandescent lamp in one side oftiic cord circuit, and means controlled by said line relay for including said lamp in a local circuit during connections and when the subscriber's telephone is not in use to cause the same to be operated, substantially as described.

12. The combination witlra tclephone'iine, of a line signal therefor, a cut-off device for the line adapted when op erated to render said signal inoperative, acord circuit to establish connections with the line for conversational purposes, a common source oi current associated with the cord circuit and arranged to semi current over the line for talking purposcs'whcn a connection exists, and a supervisory signal associated with the cord circuit, said cut-oil.

device being operaied bycurre'ut from said source over one side of said cord circuit aml the supervisory signal by current over the other side of the some, the circuits of both saidcutoif device and said supervisory signal bei 11;; local to the central oiliec, substautialiy'as described.

13. The combination with a telephone line, of a line sig- 'nal therefor, a cut otf dcvieefor the line adapted when operated to render said signal inoperative, a cord circuit to cstnbiish.connections for conversational purposes, 'a common source of current associated with the cord circuit and,..

arranged to semi current over the telephone line for talking purposes'whcn a connection exists, said cut-on device being operated bycurrcnt from said sourccover one talking strand of said cord circuit, and a supervisory signal located-in the other talking strand of the cord circuit and operated by a current thereover, substantially as de,

scribed.

14. The comb i iation with a telephone line, of a line signal therefor, a cut-off device for the line adapted when opcrnicd to render said signal inoperative; a cord circuit to establish connections with the line for convcrsatl0ual purposes, a common source of" current associated with the cord circuit and arranged to send current over the line for talking purposes when a connection exists, a relay ioealcd in the telephone. line in. the path of such talking current. said cutmll device being operated by 'e rrcnt from said source over one side only of said cord circuit, and a supervisory signal associated with thecord circuit and conrelay in the line, substantially as delfi. in :r telephone system, the combination with a tria phone line, of a cordfclreuit to establish connections for conversation, a central common source of current to sup ply cur nt over the limbs of the telephone line for con versaiion, and a supervisory signal for the cord elreuii: in the path oi such supply current, said signal receiving in sulilcient current to operate the same during eonversaiiou. but receiving sullicient current from said source to operaie the same when the subscriber's telephone is not in use, subslanthilly as described.

10. in a ielcphune system, the combination wiih a teicphoue line, of a cord circuit to establish conversational &

connections therewith. a central common source of current to supply current over the limbs 01 the telephone line to energize the transmitter, and a supcrvl, try signal for the curd circuit inthe path of such transmitter cnergization current suitl tl receiving insuliicient current to operate the same (till 11:; crmversation, but receivin; suflicient current l'rtuin 'tt source to operate the same when the subscribers telephone is notin use, substantially as described.

'17. in :1 telephone system.

the combination with a telephone line, of a cord circuit extending in two limbs adapt- "(I to be connected with the limbs of the telephone line for (utH'el'stliiwlL a central source of current to furnish currcul over the strands of said cord circuit and the limbs of the telephone line to energize the substation transmitter duri conver ition. a normally inert supervisory sig nul for thecord rucuit in the path of such current (luring cmirersation, Silil] signal receiving insutlicieut current to operate the same during; conversation, but; receiving current over a local circuit sutlicient to operate the same dur ing the connec on when the subscribers telephone is not in use, substantially as described.

18. In a telephone system, the combination with a telephone line. of a cord circuit to establish connection for conversation, a central common source of current to sup ply energy to the telephone line during conversation, and a normally inert supervisory signal for the cord circuit placed in the path of current from said source, said signal being inert during conversation but actuated over a circuit local to the central oltice and including a portion of the talking circuit: during the connection when the sub srribers telephone is not in use. substantially as de scribed.

Signed by me at Chicago, nois, this 12th day of June,

county of Cook, State of Illi- WILLIAM W. DEAN. Witnesses Rom-nu" Luwts Aims, Em A Gunmen. 

